The present invention relates to an image communication method and apparatus and, more particularly, to an image communication method and apparatus for receiving and processing a compressed image file such as a JPEG file.
Conventional facsimile apparatuses have been mainly designed for monochromatic image communication. However, as printers and scanners have become capable of color processing with advances in image processing techniques, color documents have become widespread, and the need for color image communication has grown in the field of facsimile apparatuses.
Under the circumstances, facsimile apparatuses capable of communicating color images by unique procedures came on the market, and color communication procedures were standardized by the ITU-T recommendations. It can therefore be expected that the color facsimile apparatus market will further expand.
A characteristic feature of a color communication procedure according to the ITU-T recommendations is that a color communication function is added to the protocol of the conventional monochromatic facsimile communication procedure to transmit color image data upon JPEG compression.
According to this color communication procedure, the main scanning sizes allowed for transmission correspond to standard-size sheets, i.e., A4, B4, and A3 sheets. That is, according to this specification, only originals having predetermined main scanning sizes can be transmitted. If, for example, the size of transmission image is smaller than the predetermined size, a JPEG file must be created after the main scanning size is justified to a standard length by, for example, adding white pixels.
A main scanning size can be defined in the header of a JPEG file. A color facsimile apparatus complying with the above ITU-T recommendations may receive a JPEG file having a main scanning size different from the main scanning size declared in the communication protocol. In this case, since the main scanning length of the JPEG file is recognized as a standard length, the file cannot be normally decoded, resulting in a printout failure.
In this case, the color facsimile apparatus generally has a memory reception function, and printing often starts after the JPEG file is received. In the receiving apparatus, therefore, an error occurs in printing operation even though communication is normally terminated.
The transmitting apparatus recognizes that transmission is normally terminated, in spite of the fact that the transmitted facsimile file cannot be printed on the receiving side.
The present invention has been proposed to solve the conventional problems, and has as its object to provide an image communication method and apparatus which can process an image of a received compressed image file such as a JPEG file in an appropriate main scanning length.
According to the present invention, the foregoing object is attained by providing an image communication apparatus for communicating image data with another apparatus on the basis of a communication protocol including declaration of a main scanning size, comprising: reception means for receiving a compressed image file including information indicating that a main scanning size is a first size; main scanning size control means for setting the first size as a main scanning size when a second size declared as a main scanning size in the communication protocol differs from the first size; and image processing means for processing the compressed image file on the basis of the set main scanning size.
It is another object of the present invention to provide an image communication method and apparatus which can print out an image of a received compressed image file such as a JPEG file on a printing medium without any omission.
According to the present invention, the foregoing object is attained by further providing an image communication apparatus for communicating image data with another apparatus on the basis of a communication protocol including declaration of a main scanning size, comprising: reception means for receiving a compressed image file including information indicating that a main scanning size is a first size; main scanning size control means for setting the first size as a main scanning size when a second size declared as a main scanning size in the communication protocol differs from the first size; selection means for selecting a printing medium on which printing can be performed in the set main scanning size; decompression means for decompressing the compressed image file on the basis of the set main scanning size; and output means for outputting the decompressed image data on the selected printing medium.
It is another object of the present invention to provide an image communication method and apparatus which interrupts communication and takes appropriate measures when an image of a received compressed image file such as a JPEG file cannot be appropriately printed out.
According to the present invention, the foregoing object is attained by further providing an image communication apparatus for communicating image data with another apparatus on the basis of a communication protocol including declaration of a main scanning size, comprising: reception means for receiving a compressed image file including information indicating that a main scanning size is a first size; and communication control means for interrupting communication with said another apparatus when a second size declared as a main scanning size in the communication protocol differs from the first size.
In accordance with the present invention as described above, the invention is particularly advantageous that an image of a received compressed image file such as a JPEG file can be processed in an appropriate main scanning length.
In addition, an image of a received compressed image file such as a JPEG file can be printed out on a printing medium without any omission.
Furthermore, when an image of a received compressed image file such as a JPEG file cannot be appropriately printed out, communication is interrupted, and appropriate measures can be taken.